Nope. Then again, that's kind of the point: the Mac Mini is a "Small Form Factor" class of PC. The idea being that you want to shove as much computing power as you can into as small a space as you can. It is far easier to do this with a CPU that uses less electricity (thereby allowing for a smaller power supply) and requires less active cooling equipment (thereby allowing for smaller fans).
It would be nice, I think, for Apple to start selling devices again with desktop CPUs. But yeah, the Mini is not the right vehicle for that sort of hardware.
Technically, the Mac Pro is using Xeon CPUs, which are designed and marketed for workstation use, rather than desktop use. (In general, Xeons perform better than i5/i7 class CPUs for massively multithreaded tasks, but worse for single-thread tasks.)